At this years DragonCon Richard Dean Anderson gave a very interesting insight into why they used hand doubles in some of the closeup shots in MacGyver episodes.

In his own words he explained that his constant playing with the SAKs between takes resulted in many cuts and slice scares on his fingers which were eventually considered too "gnarly" to use in close ups, so they got his brother to be a hand double for the close ups.

Watch the full interview here.

Really interesting, I had never suspected this fact.

The hands of his brother must are very similar to his hands, in particular the thumbs.

Hmm, interesting. Though I had heard hand doubles were used, I never knew the reason before this.

Very interesting, I never knew that, I always thought it was RDA's hands.

Could explain the use of different SAKs in one scene or episode?
If his brother just stepped in with the SAK he was holding to do the shot..